Question #1: What is meant by "outgassing" of a kapton label?
Anwer #1: We all love the smell of a new car...there's nothing quite like it. One year later...have you noticed the haze on the windows, even when you have never allowed ANYONE to smoke in your car? The lovely "new car smell" is an example of OUTGASSING, and the foggy window is typical of the long term effects, a haze deposited on surfaces. Many materials will emit gases under heat, such as the heat of the sun on the interior of your car.
These "volatile" materials are present in almost all polymeric/synthetic matertials, such as coatings, films, and adhesives. As heat is applied, the volatile organic compounds (or VOC's) evaporate from (in the case at hand) the polyimide or kapton label.The gaseous molecules are free to be redeposited on a cooler surface, such as a car window, mirror, or any other surface.
In the case of labels, the VOC's include small amounts of residual solvents from the coating process, plasticers, additives, and unreacted monomer from the variety of polymerizations used to create the materials.
Of course, if excessive heat is applied, the outgassing becomes due to chemical decomposition of the label materials. But, that discussion is for another series of FAQ's HEAT THINGS UP or email Technical Support
Question #2: Why has outgassing become such a demanding requirement in the disk drive industry?
Answer #2: Hard disk drive manufacturers have not only increased memory capacity in disk drive assemblies, and have dramatically increased read/write rates. These performance advances have also greatly increased the sensitivity of the head/disk interface to particulate and chemical contamination. Coupled with higher spindle speeds, which generate increased heat, label and tape materials inside the drive mechanism may outgas more, depositing residue on critical surfaces in the drive assemblies.
These changes in head technology require a new breed of electronically clean adhesives which control outgassing and limit corrosion due to trace contaminants. Polyonics made three major technology improvements in its label materials for identification of disk drives:
• reducing VOCs by weight;
• eliminating acrylic acid which causes head corrosion and media fogging;
• developing release liners that are organo-tin and/or silicone free.
Each disk drive manufacturer has different specifications for VOC’s, acrylic acid, silicones, particulate, and ionic contamination. Polyonics is well-equipped to handle each unique requirement. For more information, or to discuss specific testing or labeling needs, please contact Technical Support
Question #3: What is the importance of outgassing in applications for the aerospace industry, and NASA?
Answer #3: Outgassing of VOC's as discussed in Question #1 above is exacerbated in outer space due to the major decrease in atmospheric pressure,i.e. high vacuum. Volatile materials boil at lower temperatures under reduced pressure. So, what might have been a high boiling VOC on Earth, may become very low boiling, i.e. easily outgassed, in outer space. In addition to fogging up optics, windows, mirrors and the like, the outgassing may also cause adhesive failure of labels, allowing them to be "blown off" the objects they are adhered to, thereby rendering them useless as identifiers.
For more information see NASA OUTGASSING, or contact Technical Support
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